Frequently Asked Questions about the Clinical Tables Search Service

The Clinical Table Search Service (CTSS) is open to the general public and free of charge. However, neither the names of the National Library of Medicine (NLM), the Lister Hill National Center for Biomedical Communications (LHNCBC), the National Institutes of Health (NIH), nor the names of any of the software contributors may be used to endorse or promote products derived from this service without specific prior written permission.

Additionally, some datasets, such as LOINC, have their own terms of use. In the main page of this website, the source of each dataset is listed under the "Details" column, along with such policies and terms of use as are known to us.

  1. How can I be notified about changes and updates to this service?

    Sign up for the announcements list by sending the message "subscribe NLM-CLINICALTABLES-ANNOUNCE" (no subject needed) to listserv@list.nih.gov.

  2. How do I contact you or file an issue report?

    For general inquiry, please use the "NLM Support Center" link at the bottom of this page. For issue reporting or improvement suggestions, please use the GitHub issue tracker.

  3. What's the expected or guaranteed level of service availability?

    Unfortunately, we are unable to promise any minimum level of availability. However, we have designed the Clinical Table Search Service to be as robust as we could. It currently runs on multiple servers with a co-location for failover, and we perform rolling updates whenever possible to minimize service disruptions. Additionally, the service is monitored by an external service which sends us outage alerts.

  4. Is there any limit on how many requests that may be submitted?

    Yes. The advised maximum request rate is 25 requests per second. This is a soft limit and the enforced limit may be higher depending on the system load at the time. If you are sending more than the advised limit, please make sure to check the HTTP status code and the relevant response headers ("X-RateLimit-Limit", "Retry-After") and deal with the outcome properly. The service may respond with status code 503 if the system is overwhelmed regardless of your request rate.

    It's always a good practice to be mindful of the other users and limit the request rate if possible. If your request rate is expected to exceed 50 requests/second on a regular basis, we'd appreciate it if you could give us a heads-up using the "NLM Support Center" link at the bottom of this page.

    Please be advised that we reserve the right to make changes to the request rate policy with or without prior notice. It's a good idea to subscribe to our announcement list (details see question 1 above) to keep you updated on significant changes.

  5. How much does it cost to use the service?

    The CTSS service is free of charge for anyone to use.

  6. Is registration required to use this service?

    Registration is not required to use this service. However, to ensure the service has sufficient capacity for all users, please contact us if your usage is expected to exceed 50,000 calls per day by using the "NLM Support Center" link at the bottom of the page. Regardless of the usage levels, we would love to hear your stories on how the service is used, which would help us in improving the service to better serve your needs. Sign up for the announcements list to stay updated on new features, major changes, and potential service disruptions. See question #1 above on how to sign up.

  7. Citation and Acknowledgement?

    If you are publishing research that used this service, we'd appreciate it if you could include a citation that acknowledges it.

  8. What information do you collect or log?

    We log information commonly logged by most web servers, such as the IP address, the complete request URL (including the search parameters), etc. Do NOT include any PHI (Protected Health Information) or PII (Personally Identifiable Information) information in your requests.

  9. Is there any service level guarantee?

    No. THIS SERVICE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED GUARANTEE, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.